1. Field of Invention
This invention relates to the mast and rigging of sailboats, particularly yachts and sailboats of the racing and cruising type having weighted keels.
2. Description of Prior Art
When a sailboat's destination is upwind the vessel sails at about a 45.degree. angle from the wind's direction and zigzags or tacks back and forth to arrive at that destination. When this is done pressure of the wind is exerted against the sails which are supported by the mast and the mast's supporting stays and rigging forcing the vessel to incline or heel. This is counteracted by the righting moment of the ballasted sailboat, enabling the sailboat to move in a forward direction. The lighter the mast, rigging and sails are, and the deeper the ballast weight, the faster the vessel with a conventional fixed mast will go. What this has done to the sport of sailing is created very light but weak masts and rigging and very deep, heavy keels that are unsound.
By inclining a sailboat's mast to windward the weight of the sailboat's mast and rigging act as righting moment. The heavier and stronger the rig the more righting moment can be exerted by the rig. By doing this less righting moment is required of the ballast keel, so that it can be made shallower and stronger.
Several methods have been proposed for inclining, pivoting or swinging a mast hinging on deck. U.S. Pat. Nos. 3,903,827 to Marcil (1975), 4,117,797 to Kelly (1978), 5,392,727 to Christensen (1995), 5,509,368 to Wald (1996) and 5,570,651 to Schiff(1996), all disclose methods for inclining a mast based on the mast being hinged on the deck. This places more strain on the supporting stays and a great strain and weight at the hinge point. Hinging the mast on deck also requires a complicated shroud adjustment mechanism that is expensive to build and service.
Other methods have been proposed wherein the mast passes through the deck and are somewhat supported by the hull. U.S. Pat. Nos. 4,638,755 to Butka (1987) and 3,985,106 to Ross (1976) are of this principle. These methods have not taken into account the load that is put on the supporting stays when the mast in inclined. In these designs when the mast is inclined the lateral supporting stays or shrouds move closer to the center of the mast. Their effectiveness is greatly reduced because the angle of support is lessened. The shrouds must be tensioned independently and separately, which is very complicated to engineer.